1. Field of the Invention
The present invention relates generally to a microscope and more specifically relates to a microscope adapted for use by two or more operators during surgical operations and having a main objective and downstream optical systems for changing the level of magnification and for adjusting the plane of focus.
2. Description of the Prior Art
Microscopes are used, for example, in microsurgical operations within the clinical sector. As a result of progressively more complex surgical operating methods, it is often necessary for more than one operator to be able to work simultaneously at a surgical operating site. Moreover, in the various surgical operating disciplines, it is also often necessary for surgical operators to individually arrange their working posture and position in working relation to the subject patient.
A surgical operating microscope for two surgeons is disclosed, for example in DE 2,949,429. This patent discloses a surgical operating microscope having a main objective and three separately executed observation beam paths downstream of the main objective for two observation tubes. In order to construct two stereoscopic observation beam paths, one of the three beam paths is used jointly. As a result, it is not possible to independently adjust the image magnification of one stereoscope observation beam path without simultaneously adjusting the image magnification of the other stereoscopic observation beam path.
DE 3,333,471 discloses a surgical operating microscope wherein the observation beam paths are capable of individual settings. This is accomplished by two separate microscopes that are disposed at a right angle relative to each other with each microscope exhibiting an objective, a magnification changing device and a binocular tube. By means of a mirror that is partially transparent and disposed at 45.degree., the light coming from the object is directed via the two objectives into the respective separate observation beam paths. Accordingly, while advantageous from the perspective of independent magnification control, this construct nevertheless suffers from a particular disadvantage stemming from the use of a partially transparent mirror that reduces the light available for observation by 50%.
DE 3,602,095 and DE 3,523,639 also disclose operating microscopes for use by two surgical operators. In both microscopes, there is a common main objective and observation beam paths that are executed separately from one another. In order to permit both operators to have the same view of the object field to be investigated, irrespective of the particular location, one of the stereoscopic beam paths is rotated about the optical axis of the main objective using additional optical means. Both stereoscopic beam paths exhibit zoom objectives to alter the image magnification. In addition to the considerable mechanical complexity, these microscopes suffer from a further disadvantage in that it is not possible to carry out independent focusing of the individual observation beam paths.
U.S. Pat. No. 4,138,191 discloses a surgical operating microscope for use by two operators, in which two separate stereoscope observation beam paths are formed using a common main objective. This reference also discloses the possibility of using an additional separate beam path for making photographic exposures. This microscope, however, also suffers from the disadvantage of lacking the capability of independently focusing the two stereoscopic observation beam paths.
DE 3,202,075 discloses an optical system with variable intercept length and focal length for surgical operating microscopes with a main objective of fixed focal length. The internal focusing provided in this microscope includes a zoom system with a plurality of lens groups that is capable of movement along the optical axis of the main objective in order to retain the stereoscopic observation image in the course of focusing and in the course of the changing of the image magnification with concurrent movement perpendicular to the optical axis of the main objective. The curved movement resulting from this gives rise to a high degree of mechanical complexity in the precise guiding and coupling of the lens elements.